Olefin-based polymer preparation method and olefin-based polymer prepared thereby and having excellent processability

Abstract

The present invention relates to a method for preparing an olefin-based polymer and an olefin-based polymer prepared thereby and having excellent processability. The olefin-based polymer prepared from the composite metallocene catalyst according to one exemplary embodiment of the present invention has excellent processability since the olefin-based polymer has a large bimodal or multimodal molecular weight distribution. And an olefin-based polymer film prepared by molding the polymer can exhibit excellent quality in which gel production is suppressed.

Description

Technical Field

[0001] The present invention relates to a method for preparing an olefin-based polymer and an olefin-based polymer prepared thereby and having excellent processability. Specifically, the present invention relates to a method for preparing an olefin-based polymer in the presence of a compound metallocene catalyst and an olefin-based polymer prepared thereby and having a large bimodal or multimodal molecular weight distribution to have excellent processability and allow the preparation of a film with suppressed gel formation. Background Art

[0002] Polyolefin-based polymers are used in various ways in real life as materials for shopping bags, greenhouses, fishing nets, cigarette wrappers, ramen bags, yogurt bottles, battery cases, automobile bumpers, interior materials, shoe soles, washing machines, etc.

[0003] Conventionally, polyolefin-based polymers (such as polyethylene, polypropylene, and ethylene α-olefin copolymers, and their copolymers) are prepared by a heterogeneous catalyst (such as a Ziegler-Natta catalyst formed from a titanium compound and an alkyl aluminum compound).

[0004] Recently, methods for preparing polyolefins using metallocene catalysts, which are homogeneous catalysts with very high catalytic activity, have been studied. A metallocene catalyst is a compound in which a ligand such as cyclopentadienyl, indenyl, or cycloheptadienyl coordinates with a transition metal or a transition metal halide compound, and has a sandwich structure as a basic form. Herein, it has various molecular structures depending on the ligand form and the type of central metal.

[0005] Since in the Ziegler-Natta catalyst, which is a heterogeneous catalyst, the metal component as an active site is dispersed on the surface of an inert solid, the characteristics of the active sites of the Ziegler-Natta catalyst are not uniform; however, since a metallocene catalyst is a compound having a specific structure, a metallocene catalyst is called a single-site catalyst having the same polymerization characteristics at all active sites.

[0006] The metallocene catalyst itself allows easy copolymerization, can adjust the three-dimensional structure of the polymer according to the catalyst symmetry, and the polymer prepared therefrom has a narrow molecular weight distribution and a uniform comonomer distribution.

[0007] However, polymers prepared with metallocene catalysts have excellent mechanical strength but low processability due to their narrow molecular weight distribution. To solve this problem, various methods exist, such as changing the molecular structure of the polymer or broadening the molecular weight distribution. For example, U.S. Patent No. 5,272,236 discloses that using a catalyst that introduces long chain branches (LCBs) as branches into the main chain of the polymer improves the processability of the polymer, but gels may be generated due to the entanglement of the long chain branches.

[0008] Generally, it is known that as the molecular weight distribution (MWD) or melt flow ratio (MFR) of polyolefins increases, the processability improves, but a large MWD or MFR of polyolefins does not necessarily mean excellent processability in the high-speed region.

[0009] Therefore, there is a need for an olefin-based polymer that has a large bimodal or multimodal molecular weight distribution, has excellent high-speed processability, and allows the preparation of films with suppressed gel formation. SUMMARY OF THE INVENTION

[0010] TECHNICAL PROBLEM

[0011] An object of the present invention is to provide a method for preparing an olefin-based polymer in the presence of a composite metallocene catalyst and an olefin-based polymer prepared thereby, which has a large bimodal or multimodal molecular weight distribution, has excellent processability, and allows the preparation of films with suppressed gel formation.

[0012] TECHNICAL SOLUTION

[0013] In one general aspect, a method for preparing an olefin-based polymer includes: polymerizing ethylene and at least one α-olefin in the presence of a composite metallocene catalyst to obtain an olefin-based polymer, the composite metallocene catalyst including: (a) at least one first transition metal compound selected from transition metal compounds represented by the following Chemical Formulas 1 to 4; (b) at least one second transition metal compound selected from transition metal compounds represented by the following Chemical Formula 5; and (c) a cocatalyst compound, wherein the olefin-based polymer has a density of 0.930 g / cm 3 to 0.970 g / cm 3 , a melt index (I 2.16 ) measured at 190 °C with a load of 2.16 kg of 0.1 g / 10 min to 2.0 g / 10 min, a weight average molecular weight of 100,000 g / mol to 150,000 g / mol, and 1,500 seconds when measured with a capillary rheometer -1a shear rate of or greater, defined by Equation 1 below, at which melt fracture or sharkskin phenomenon occurs:

[0014] [Equation 1]

[0015]

[0016]

[0017] In the above equation, is the apparent shear rate (seconds -1 ), V is the volumetric flow rate generated by the piston (mm 3 / second), and R is the radius of the circular hole capillary (mm),

[0018] In the above chemical formula, l1 and m1 are independently integers from 0 to 5,

[0019] l2, l3, l4, and m2 are independently integers from 0 to 4,

[0020] m3 and m4 are independently integers from 0 to 2,

[0021] p is the oxidation state of M and is +3, +4, or +5,

[0022] q is the formal charge of the YZL ligand and is 0, -1, -2, or -3,

[0023] M are independently titanium (Ti), zirconium (Zr), or hafnium (Hf),

[0024] X are independently halogen, C 1-20 alkyl, C 2-20 alkenyl, C 2-20 alkynyl, C 6-20 aryl, C 1-20 alkyl C 6-20 aryl, C 6-20 aryl C 1-20 alkyl, C 1-20 alkyl amido, or C 6-20 aryl amido,

[0025] Q are independently carbon (C), silicon (Si), germanium (Ge), or tin (Sn),

[0026] Q' is an anionic leaving group and is independently hydrogen, substituted or unsubstituted C 1-40 hydrocarbyl, substituted or unsubstituted C 1-40 heterohydrocarbyl, heteroatom, or halogen,

[0027] Q” is substituted or unsubstituted C 2-4 alkylene,

[0028] L is a Group 15 or Group 16 element, and is preferably nitrogen,

[0029] Y is a Group 15 element, preferably nitrogen or phosphorus, and more preferably nitrogen,

[0030] Z is a Group 15 element, preferably nitrogen or phosphorus, and more preferably nitrogen,

[0031] R1 to R4, R7, R8, R 18 and R 19 are each independently a substituted or unsubstituted C 1-20 alkyl, a substituted or unsubstituted C 2-20 alkenyl, a substituted or unsubstituted C 6-20 aryl, a substituted or unsubstituted C 1-20 alkyl C 6-20 aryl, a substituted or unsubstituted C 6-20 aryl C 1-20 alkyl, a substituted or unsubstituted C 1-20 heteroalkyl, a substituted or unsubstituted C 3-20 heteroaryl, a substituted or unsubstituted C 1-20 alkylamido, a substituted or unsubstituted C 6-20 arylamido, or a substituted or unsubstituted C 1-20 silyl, provided that these groups may or may not be independently connected to adjacent groups to form a substituted or unsubstituted, saturated or unsaturated C 4-20 ring,

[0032] R5, R6, R9 and R 10 are each independently a substituted or unsubstituted C 1-20 alkyl, a substituted or unsubstituted C 2-20 alkenyl, a substituted or unsubstituted C 6-20 aryl, a substituted or unsubstituted C 1-20 alkyl C 6-20 aryl, a substituted or unsubstituted C 6-20 aryl C 1-20 alkyl, a substituted or unsubstituted C 1-20 heteroalkyl, a substituted or unsubstituted C 3-20 heteroaryl, a substituted or unsubstituted C 1-20 alkylamido, a substituted or unsubstituted C 6-20 arylamido, or a substituted or unsubstituted C 1-20 silyl, provided that R5 and R6 and R9 and R 10may or may not be connected to each other independently to form a substituted or unsubstituted, saturated or unsaturated C 2-20 ring,

[0033] R 11 and R 12 are each independently a C 1-20 hydrocarbyl group or a heteroatom-containing group, wherein the heteroatom is silicon, germanium, tin, lead or phosphorus, or R 11 and R 12 may be connected to each other,

[0034] R 13 is absent, or is hydrogen, C 1-20 alkyl, halogen or a heteroatom-containing group,

[0035] R 14 and R 15 are each independently an alkyl group, an aryl group, a substituted aryl group, a cycloalkyl group, a substituted cycloalkyl group or a polycyclic system, and

[0036] R 16 and R 17 are each independently absent or may be hydrogen, alkyl, halogen, heteroatom, hydrocarbyl or a heteroatom-containing group.

[0037] In a specific example of the present invention, the molar ratio between the first transition metal compound and the second transition metal compound may be in the range of 10:1 to 1:10.

[0038] In a specific example of the present invention, the transition metal compound of Formula 1 may be at least one of the transition metal compounds represented by the following Formulas 1-1 to 1-4, the transition metal compound of Formula 2 may be at least one of the transition metal compounds represented by the following Formulas 2-1 to 2-3, the transition metal compound of Formula 3 may be the transition metal compound represented by the following Formula 3-1, and the transition metal compound of Formula 4 may be the transition metal compound represented by the following Formula 4-1:

[0039]

[0040]

[0041] wherein n-Bu is n-butyl, t-Bu is tert-butyl, and Ph is phenyl.

[0042] In a specific example of the present invention, the transition metal compound of Formula 5 may be the transition metal compound represented by the following Formula 5-1:

[0043] [Formula 5-1]

[0044]

[0045] In a specific example of the present invention, the cocatalyst compound may include at least one selected from the compounds represented by the following Chemical Formula 6, the compounds represented by the following Chemical Formula 7, and the compounds represented by the following Chemical Formula 8:

[0046] [Chemical Formula 6]

[0047]

[0048] [Chemical Formula 7]

[0049]

[0050] [Chemical Formula 8]

[0051] [L-H] + [Z(A)4] - or [L] + [Z(A)4] -

[0052] In the above Chemical Formula 6, n is an integer of 2 or greater, and R a is a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a halogen-substituted hydrocarbon group having 1 to 20 carbon atoms,

[0053] In the above Chemical Formula 7, D is aluminum (Al) or boron (B), and R b , R c and R d are each independently a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogen-substituted hydrocarbon group having 1 to 20 carbon atoms, or an alkoxy group having 1 to 20 carbon atoms, and

[0054] In the above Chemical Formula 8, L is a neutral or cationic Lewis base, [L-H] + and [L] + are Bronsted acids, Z is a Group 13 element, and A is each independently a substituted or unsubstituted aryl group having 6 to 20 carbon atoms or a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms.

[0055] In a preferred specific example of the present invention, the compound represented by Chemical Formula 6 may be at least one selected from the following: methylaluminoxane, ethylaluminoxane, isobutylaluminoxane, and butylaluminoxane.

[0056] In a preferred specific example of the present invention, the compound represented by Chemical Formula 7 may be at least one selected from the following: trimethylaluminum, triethylaluminum, triisobutylaluminum, tripropylaluminum, tributylaluminum, dimethylaluminum chloride, triisopropylaluminum, tri-sec-butylaluminum, tricyclopentylaluminum, tripentylaluminum, triisopentylaluminum, trihexylaluminum, trioctylaluminum, ethyldimethylaluminum, methyldiethylaluminum, triphenylaluminum, tri-p-tolylaluminum, dimethylmethoxyaluminum, dimethylethoxyaluminum, trimethylboron, triethylboron, triisobutylboron, tripropylboron, and tributylboron.

[0057] In a preferred specific example of the present invention, the compound represented by Chemical Formula 8 may be at least one selected from the following: triethylammonium tetraphenylborate, tributylammonium tetraphenylborate, trimethylammonium tetraphenylborate, tripropylammonium tetraphenylborate, trimethylammonium tetrakis(p-tolyl)borate, trimethylammonium tetrakis(o,p-dimethylphenyl)borate, tributylammonium tetrakis(p-trifluoromethylphenyl)borate, trimethylammonium tetrakis(p-trifluoromethylphenyl)borate, tributylammonium pentakis(pentafluorophenyl)borate, N,N-diethylaniline tetraphenylborate, N,N-diethylaniline pentakis(pentafluorophenyl)borate, diethylammonium pentakis(pentafluorophenyl)borate, triphenyl tetraphenylaluminate trimethyl tetraphenylaluminate triethylammonium tetraphenylaluminate, tributylammonium tetraphenylaluminate, trimethylammonium tetraphenylaluminate, tripropylammonium tetraphenylaluminate, trimethylammonium tetrakis(p-tolyl)aluminate, tripropylammonium tetrakis(p-tolyl)aluminate, triethylammonium tetrakis(o,p-dimethylphenyl)aluminate, tributylammonium tetrakis(p-trifluoromethylphenyl)aluminate, trimethylammonium tetrakis(p-trifluoromethylphenyl)aluminate, tributylammonium pentakis(pentafluorophenyl)aluminate, N,N-diethylaniline tetraphenylaluminate, N,N-diethylaniline pentakis(pentafluorophenyl)aluminate, diethylammonium pentakis(pentafluorophenyl)aluminate, triphenyl tetraphenylaluminate trimethyl tetraphenylaluminate tripropylammonium tetrakis(p-tolyl)borate, triethylammonium tetrakis(o,p-dimethylphenyl)borate, triphenylcarbenium tetrakis(p-trifluoromethylphenyl)borate and triphenylcarbenium pentakis(pentafluorophenyl)borate.

[0058] In a specific example, the supported metallocene catalyst may further comprise a support for supporting the supported complex transition metal compound, the cocatalyst compound, or both.

[0059] In a specific example of the present invention, the support may include at least one selected from silica, alumina, and magnesia.

[0060] In this text, based on 1 g of the carrier, the total amount of the composite transition metal compound supported on the carrier can be from 0.001 mmol to 1 mmol, and based on 1 g of the carrier, the total amount of the cocatalyst compound supported on the carrier can be from 2 mmol to 15 mmol.

[0061] In a specific example of the present invention, the α-olefin can be at least one selected from the following: propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, and 1-hexadecene. Preferably, the α-olefin can be 1-hexene.

[0062] In a specific example of the present invention, the polymerization of ethylene and at least one α-olefin can be carried out by gas-phase polymerization, and specifically, the polymerization of ethylene and at least one α-olefin can be carried out in a gas-phase fluidized bed reactor.

[0063] In another general aspect, there is provided an olefin-based polymer prepared by the above preparation method, wherein the olefin-based polymer has a density of 0.930 g / cm 3 to 0.970 g / cm 3 , a melt index (I 2.16 ) measured at 190 °C under a load of 2.16 kg of from 0.1 g / 10 min to 2.0 g / 10 min, a weight-average molecular weight of 100,000 g / mol to 150,000 g / mol, and a shear rate of 1,500 s -1 or greater defined by Equation 1 above, at which melt fracture or sharkskin phenomenon occurs.

[0064] In a specific example of the present invention, the ratio (melt flow ratio; MFR) of the melt index (I 21.6 ) measured at 190 °C under a load of 21.6 kg to the melt index (I 2.16 ) measured under a load of 2.16 kg of the olefin-based polymer is from 30 to 200.

[0065] In a specific example of the present invention, when the olefin-based polymer is represented by a Van Gurp-Palmen plot, an inflection point may exist.

[0066] In a specific example of the present invention, when the olefin-based polymer is formed into a film with a thickness of 30 μm to 60 μm by blown film molding, the gel index of the film can be 1 or less, and the gel index is defined by the number of gels having a size of 0.05 mm or greater present in a random film area of 5 cm × 5 cm.

[0067] In yet another general aspect, an olefin-based polymer film prepared by molding an olefin-based polymer is provided, wherein when the olefin-based polymer is molded into a film having a thickness of 30 μm to 60 μm by blown film molding, the gel index of the film is 1 or less, and the gel index is defined by the number of gels having a size of 0.05 mm or more present in a random film area of 5 cm × 5 cm.

[0068] Advantageous Effects

[0069] Since the olefin-based polymer prepared from a metallocene composite catalyst according to an exemplary embodiment of the present invention has a large bimodal or multimodal molecular weight distribution, it has excellent high-speed processability, and an olefin-based polymer film prepared by molding the polymer can exhibit excellent quality with suppressed gel formation. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 Van Gurp-Palmen diagrams of the olefin-based polymers of Example 3, Comparative Examples 6 and 7, and Control Example 1.

[0071] Figure 2 Graphs showing the GPC analysis results of the olefin-based polymers of Example 3, Comparative Examples 6 and 7, and Control Example 1. DETAILED DESCRIPTION

[0072] Hereinafter, the present invention will be described in more detail.

[0073] Method for Preparing Olefin-Based Polymer

[0074] According to an exemplary embodiment of the present invention, a method for preparing an olefin-based polymer is provided, the method comprising: polymerizing ethylene and at least one α-olefin in the presence of a metallocene composite catalyst, the metallocene composite catalyst comprising: (a) at least one first transition metal compound selected from transition metal compounds represented by Chemical Formulas 1 to 4 below; (b) at least one second transition metal compound selected from transition metal compounds represented by Chemical Formula 5 below; and (c) a cocatalyst compound:

[0075]

[0076]

[0077] [Chemical Formula 5]

[0078]

[0079] In the above chemical formula, l1 and m1 are each independently an integer from 0 to 5. Preferably, l1 is 1, and m1 are each independently an integer from 1 to 5.

[0080] l2, l3, l4, and m2 are each independently an integer from 0 to 4. Preferably, l2, l3, l4, and m2 are each independently 0 or 1.

[0081] m3 and m4 are each independently an integer from 0 to 2. Preferably, m3 and m4 are each independently 0 or 1.

[0082] p is the oxidation state of M and is +3, +4, or +5.

[0083] q is the formal charge of the YZL ligand and is 0, -1, -2, or -3.

[0084] M is a Group 4 transition metal of the periodic table. Specifically, M can be titanium (Ti), zirconium (Zr), or hafnium (Hf), and more specifically zirconium.

[0085] X are each independently halogen, C 1-20 alkyl, C 2-20 alkenyl, C 2-20 alkynyl, C 6-20 aryl, C 1-20 alkyl C 6-20 aryl, C 6-20 aryl C 1-20 alkyl, C 1-20 alkylamido, or C 6-20 arylamido. Specifically, X can each independently be halogen, and more specifically chlorine (Cl).

[0086] Q are each independently carbon (C), silicon (Si), germanium (Ge), or tin (Sn). Specifically, Q are each independently carbon (C) or silicon (Si).

[0087] Q' is an anionic leaving group and is each independently hydrogen, substituted or unsubstituted C 1-40 hydrocarbyl, substituted or unsubstituted C 1-40 heterohydrocarbyl, heteroatom, or halogen. Specifically, Q' can be a straight-chain or branched alkyl; alkenyl; alkynyl; cycloalkyl; aryl; acyl; aroyl; alkoxy; aryloxy; alkylthio; dialkylamino; alkoxycarbonyl; aryloxycarbonyl; carbamoyl; alkyl-carbamoyl, or dialkyl-carbamoyl; acyloxy; acylamino; aroylamino; straight-chain, branched, or cyclic alkylene; or a combination thereof.

[0088] Q” is substituted or unsubstituted C 2-4 alkylene. Preferably, Q” can be ethylene (-CH2-CH2-).

[0089] L is a Group 15 or Group 16 element, and is preferably nitrogen.

[0090] Y is a Group 15 element, preferably nitrogen or phosphorus, and more preferably nitrogen.

[0091] Z is a Group 15 element, preferably nitrogen or phosphorus, and more preferably nitrogen.

[0092] R1 to R4, R7, R8, R 18 and R 19 are each independently a substituted or unsubstituted C 1-20 alkyl, a substituted or unsubstituted C 2-20 alkenyl, a substituted or unsubstituted C 6-20 aryl, a substituted or unsubstituted C 1-20 alkyl C 6-20 aryl, a substituted or unsubstituted C 6-20 aryl C 1-20 alkyl, a substituted or unsubstituted C 1-20 heteroalkyl, a substituted or unsubstituted C 3-20 heteroaryl, a substituted or unsubstituted C 1-20 alkylamido, a substituted or unsubstituted C 6-20 arylamido, or a substituted or unsubstituted C 1-20 silyl, but these groups may or may not be independently connected to adjacent groups to form a substituted or unsubstituted, saturated or unsaturated C 4-20 ring. Specifically, R1 to R4, R7, R8, R 18 and R 19 can each independently be a substituted or unsubstituted C 1-20 alkyl or a substituted or unsubstituted C 6-20 aryl.

[0093] R5, R6, R9 and R 10 are each independently a substituted or unsubstituted C 1-20 alkyl, a substituted or unsubstituted C 2-20 alkenyl, a substituted or unsubstituted C 6-20 aryl, a substituted or unsubstituted C 1-20 alkyl C 6-20 aryl, a substituted or unsubstituted C 6-20 aryl C 1-20 alkyl, a substituted or unsubstituted C 1-20 heteroalkyl, a substituted or unsubstituted C 3-20 heteroaryl, a substituted or unsubstituted C 1-20 alkylamido, a substituted or unsubstituted C6-20 an arylamide group, or a substituted or unsubstituted C 1-20 silyl group, provided that R5 and R6 and R9 and R 10 may or may not be independently joined to each other to form a substituted or unsubstituted, saturated or unsaturated C 2-20 ring. Specifically, R5 and R6 and R9 and R 10 are independently of each other a substituted or unsubstituted C 1-20 alkyl group, a substituted or unsubstituted C 2-20 alkenyl group, or a substituted or unsubstituted C 6-20 aryl group.

[0094] R 11 and R 12 are independently of each other a hydrocarbon group or a heteroatom-containing group, where the heteroatom is silicon, germanium, tin, lead or phosphorus, or R 1-20 and R 11 and R 12 may be joined to each other. Specifically, R 11 and R 12 may independently of each other be a C 1-6 hydrocarbon group.

[0095] R 13 is absent, or is hydrogen, a C 1-20 alkyl group, a halogen or a heteroatom-containing group. Specifically, R 13 may be hydrogen or methyl.

[0096] R 14 and R 15 are independently of each other an alkyl group, an aryl group, a substituted aryl group, a cycloalkyl group, a substituted cycloalkyl group or a polycyclic system. Specifically, R 14 and R 15 may independently of each other be a substituted aryl group.

[0097] R 16 and R 17 are independently of each other absent or may be hydrogen, an alkyl group, a halogen, a heteroatom, a hydrocarbon group or a heteroatom-containing group.

[0098] In a metallocene catalyst composite for olefin polymerization according to an exemplary embodiment, the molar ratio between the first transition metal compound and the second transition metal compound may be in the range of 10:1 to 1:10. When the molar ratio between the first transition metal compound and the second transition metal compound is within this range, a polyolefin-based polymer having excellent high-speed processability can be obtained, and the generation of gels in the film prepared therefrom can be suppressed.

[0099] In a specific example of the present invention, the transition metal compound of Formula 1 may be at least one of the transition metal compounds represented by the following Formulas 1-1 to 1-4, the transition metal compound of Formula 2 may be at least one of the transition metal compounds represented by the following Formulas 2-1 to 2-3, the transition metal compound of Formula 3 may be the transition metal compound represented by the following Formula 3-1, and the transition metal compound of Formula 4 may be the transition metal compound represented by the following Formula 4-1:

[0100]

[0101]

[0102] Wherein n-Bu is n-butyl, t-Bu is tert-butyl, and Ph is phenyl.

[0103] In a specific example of the present invention, the transition metal compound of Formula 5 may be the transition metal compound represented by the following Formula 5-1:

[0104] [Formula 5-1]

[0105]

[0106] In a specific example of the present invention, the cocatalyst compound may include at least one selected from the compounds represented by the following Formula 6, the compounds represented by the following Formula 7, and the compounds represented by the following Formula 8:

[0107] [Formula 6]

[0108]

[0109] In the above Formula 6, n is an integer of 2 or greater, and R a is a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a halogen-substituted hydrocarbon group having 1 to 20 carbon atoms. Specifically, R a may be methyl, ethyl, n-butyl, or isobutyl.

[0110] [Formula 7]

[0111]

[0112] In the above Formula 7, D is aluminum (Al) or boron (B), and R b 、R c and R dEach independently is a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogen-substituted hydrocarbon group having 1 to 20 carbon atoms, or an alkoxy group having 1 to 20 carbon atoms. Specifically, when D is aluminum (Al), R b , R c and R d can each independently be methyl or isobutyl, and when D is boron (B), R b , R c and R d can each be pentafluorophenyl, respectively.

[0113] [Chemical Formula 8]

[0114] [L-H] + [Z(A)4] - or [L] + [Z(A)4] -

[0115] In the above Chemical Formula 8, L is a neutral or cationic Lewis base, [L-H] + and [L] + are Bronsted acids, Z is a Group 13 element, and A each independently is a substituted or unsubstituted aryl group having 6 to 20 carbon atoms or a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms. Specifically, [L-H] + can be a dimethylaniline cation, [Z(A)4] - can be [B(C6F5)4] - , and [L] + can be [(C6H5)3C] + .

[0116] Examples of the compound represented by Chemical Formula 6 can include methylaluminoxane, ethylaluminoxane, isobutylaluminoxane, butylaluminoxane, etc., and methylaluminoxane is preferred, but not limited thereto.

[0117] Examples of the compound represented by Chemical Formula 7 include trimethylaluminum, triethylaluminum, triisobutylaluminum, tripropylaluminum, tributylaluminum, dimethylaluminum chloride, triisopropylaluminum, tri-sec-butylaluminum, tricyclopentylaluminum, tripentylaluminum, triisopentylaluminum, trihexylaluminum, trioctylaluminum, ethyldimethylaluminum, methyldiethylaluminum, triphenylaluminum, tri-p-tolylaluminum, dimethylmethoxyaluminum, dimethylethoxyaluminum, trimethylboron, triethylboron, triisobutylboron, tripropylboron, tributylboron, etc., and trimethylaluminum, triethylaluminum, and triisobutylaluminum are preferred, but not limited thereto.

[0118] Examples of the compound represented by Chemical Formula 8 may include triethylammonium tetraphenylborate, tributylammonium tetraphenylborate, trimethylammonium tetraphenylborate, tripropylammonium tetraphenylborate, trimethylammonium tetrakis(p-tolyl)borate, trimethylammonium tetrakis(o,p-dimethylphenyl)borate, tributylammonium tetrakis(p-trifluoromethylphenyl)borate, trimethylammonium tetrakis(p-trifluoromethylphenyl)borate, tributylammonium pentaphenylborate, N,N-diethylaniline tetraphenylborate, N,N-diethylaniline pentaphenylborate, diethylammonium pentaphenylborate, triphenyltetraphenylborate trimethyltetraphenylborate triethylammonium tetraphenylaluminate, tributylammonium tetraphenylaluminate, trimethylammonium tetraphenylaluminate, tripropylammonium tetraphenylaluminate, trimethylammonium tetrakis(p-tolyl)aluminate, tripropylammonium tetrakis(p-tolyl)aluminate, triethylammonium tetrakis(o,p-dimethylphenyl)aluminate, tributylammonium tetrakis(p-trifluoromethylphenyl)aluminate, trimethylammonium tetrakis(p-trifluoromethylphenyl)aluminate, tributylammonium pentaphenylaluminate, N,N-diethylaniline tetraphenylaluminate, N,N-diethylaniline pentaphenylaluminate, diethylammonium pentaphenylaluminate, triphenyltetraphenylaluminate trimethyltetraphenylaluminate tripropylammonium tetrakis(p-tolyl)borate, triethylammonium tetrakis(o,p-dimethylphenyl)borate, triphenylcarbene tetrakis(p-trifluoromethylphenyl)borate, triphenylcarbene pentaphenylborate, etc.

[0119] In one specific example, the metallocene composite catalyst for olefin polymerization may further include a support for supporting the composite transition metal compound, the cocatalyst compound, or both.

[0120] In the present disclosure, the support may include a material having hydroxyl groups on its surface, and preferably, a material having highly reactive hydroxyl and siloxane groups that has been dried to remove surface moisture may be used. For example, the support may include at least one selected from silica, alumina, and magnesia. Specifically, silica, silica-alumina, silica-magnesia, etc. dried at high temperature may be used as the support, and these generally may contain oxide, carbonate, sulfate, and nitrate components, such as Na2O, K2CO3, BaSO4, and Mg(NO3)2. In addition, these may contain carbon, zeolite, magnesium chloride, etc. However, the support is not particularly limited thereto.

[0121] The average particle size of the support may be from 10 μm to 250 μm, preferably from 10 μm to 150 μm, and more preferably from 20 μm to 100 μm.

[0122] The micropore volume of the support can be from 0.1 ml / g to 10 ml / g, preferably from 0.5 ml / g to 5 ml / g, and more preferably from 1.0 ml / g to 3.0 ml / g.

[0123] The specific surface area of the support can be from 1 m 2 / g to 1,000 m 2 / g, preferably from 100 m 2 / g to 800 m 2 / g, and more preferably from 200 m 2 / g to 600 m 2 / g.

[0124] In a preferred example, when the support is silica, the drying temperature of the silica can be from 200 °C to 900 °C. The drying temperature can be from 300 °C to 800 °C, and more preferably from 400 °C to 700 °C. When the drying temperature is lower than 200 °C, the silica has too much moisture, causing the moisture on the surface to react with the first promoter compound, while when the drying temperature is higher than 900 °C, the structure of the support may collapse.

[0125] The concentration of hydroxyl groups in the dried silica can be from 0.1 mmol / g to 5 mmol / g, preferably from 0.7 mmol / g to 4 mmol / g, and more preferably from 1.0 mmol / g to 2 mmol / g. When the concentration of hydroxyl groups is less than 0.1 mmol / g, the loading amount of the promoter decreases, while when the concentration is greater than 5 mmol / g, the catalyst components become inactivated.

[0126] Based on 1 g of the support, the total amount of the composite transition metal compound loaded on the support can be from 0.001 mmol to 1 mmol. When the ratio between the composite transition metal compound and the support satisfies the above range, an appropriate supported catalyst activity is exhibited, which is advantageous in terms of the activity retention and economic feasibility of the catalyst.

[0127] Based on 1 g of the support, the total amount of the promoter compound loaded on the support can be from 2 mmol to 15 mmol. When the ratio of the promoter compound to the support satisfies the above range, it is advantageous in terms of the activity retention and economic feasibility of the catalyst.

[0128] One or two or more supports can be used. For example, both the composite transition metal compound and the promoter compound can be loaded on one support, and the composite transition metal compound and the promoter compound can each be loaded on two or more supports. In addition, only one of the composite transition metal compound and the promoter compound can be loaded on the support.

[0129] In a specific example of the present invention, the olefin-based polymer can be a homopolymer of an olefin-based monomer or a copolymer of an olefin-based monomer and a comonomer. Preferably, the olefin-based polymer is a copolymer of an olefin-based monomer and an olefin-based comonomer.

[0130] As used herein, the olefin-based monomer can be at least one selected from the following: C 2-20 α-olefin, C 3-20 diene, C 3-20 cycloolefin, and C 4-20 cyclodiene.

[0131] For example, the olefin-based monomer can be ethylene, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, etc., and the olefin-based polymer can be a homopolymer containing only one of the above-exemplified olefin-based monomers or a copolymer containing two or more of them.

[0132] In an exemplary embodiment, the olefin-based polymer can be a copolymer of ethylene and C 3-20 α-olefin. Preferably, the olefin-based polymer can be linear low-density polyethylene in which the olefin-based monomer is ethylene and the olefin-based comonomer is 1-hexene.

[0133] In this case, the content of ethylene is preferably 55% to 99.9% by weight, and more preferably 90% to 99.9% by weight. The content of the α-olefin-based comonomer is preferably 0.1% to 45% by weight, and more preferably 0.1% to 10% by weight.

[0134] In a specific example of the present invention, the olefin-based polymer can be prepared by gas-phase polymerization, solution polymerization, slurry polymerization, etc. Preferably, the polymerization of the olefin-based monomer can be carried out by gas-phase polymerization, and more specifically, the polymerization of the olefin-based monomer can be carried out in a gas-phase fluidized bed reactor.

[0135] When the olefin-based polymer is prepared by solution polymerization or slurry polymerization, examples of the solvent to be used can include: C 5-12 aliphatic hydrocarbon solvents such as pentane, hexane, heptane, nonane, decane and their isomers; aromatic hydrocarbon solvents such as toluene and benzene; hydrocarbon solvents substituted with chlorine atoms such as dichloromethane and chlorobenzene; and mixtures thereof, but not limited thereto.

[0136] The olefin-based polymer prepared by the method for preparing an olefin-based polymer according to an exemplary embodiment of the present invention has a density of 0.930 g / cm 3 to 0.970 g / cm 3 , a melt index (I 2.16 ) measured at 190 °C under a load of 2.16 kg of 0.1 g / 10 min to 2.0 g / 10 min, a weight average molecular weight of 100,000 g / mol to 150,000 g / mol, and a shear rate defined by the following Equation 1 of 1,500 seconds -1 or greater, at which melt fracture or sharkskin phenomenon occurs:

[0137] [Equation 1]

[0138]

[0139] where is the apparent shear rate (seconds -1 ), V is the volume flow rate generated by the piston (mm 3 / s), and R is the radius of the round hole capillary (mm).

[0140] Olefin-based polymer

[0141] According to an exemplary embodiment of the present invention, there is provided an olefin-based polymer which is prepared by the above method for preparing an olefin-based polymer and has a density of 0.930 g / cm 3 to 0.970 g / cm 3 , a melt index (I 2.16 ) measured at 190 °C under a load of 2.16 kg of 0.1 g / 10 min to 2.0 g / 10 min, a weight average molecular weight of 100,000 g / mol to 150,000 g / mol, and a shear rate defined by the above Equation 1 of 1,500 seconds -1 or greater, at which melt fracture or sharkskin phenomenon occurs.

[0142] The density of the olefin-based polymer according to an exemplary embodiment of the present invention is 0.930 g / cm 3 to 0.970 g / cm 3 . Preferably, the density of the olefin-based polymer may be 0.930 g / cm 3 to 0.965 g / cm 3 , and more preferably 0.935 g / cm 3 to 0.960 g / cm 3 .

[0143] The melt index (I 2.16 ) of the olefin-based polymer according to an exemplary embodiment of the present invention, measured at 190 °C with a load of 2.16 kg, is from 0.1 g / 10 min to 1.5 g / 10 min. Preferably, the melt index of the olefin-based polymer measured at 190 °C with a load of 2.16 kg can be from 0.1 g / 10 min to 2.0 g / 10 min, and more preferably from 0.2 g / 10 min to 1.5 g / 10 min.

[0144] The weight-average molecular weight of the olefin-based polymer according to an exemplary embodiment of the present invention is from 100,000 g / mol to 150,000 g / mol. Preferably, the weight-average molecular weight of the olefin-based polymer can be from 100,000 g / mol to 145,000 g / mol, and more preferably from 100,000 g / mol to 140,000 g / mol.

[0145] In a specific example of the present invention, the ratio (melt flow ratio; MFR) between the melt index (I 21.6 ) of the olefin-based polymer measured at 190 °C with a load of 21.6 kg and the melt index (I 2.16 ) measured with a load of 2.16 kg can be from 30 to 200. Preferably, the MFR of the olefin-based polymer can be from 30 to 150, and more preferably from 40 to 135.

[0146] The shear rate defined by the following Equation 1 of the olefin-based polymer according to an exemplary embodiment of the present invention, when measured with a capillary rheometer, is 1,500 s -1 or greater, showing melt fracture or sharkskin phenomenon at said shear rate. Preferably, the shear rate showing melt fracture or sharkskin phenomenon can be 1,750 s -1 or greater, and more preferably 2,000 s -1 or greater.

[0147] [Equation 1]

[0148]

[0149] where is the apparent shear rate (s -1 ), V is the volume flow rate generated by the piston (mm 3 / s), and R is the radius of the round-hole capillary (mm).

[0150] Melt fracture or sharkskin generally refers to the appearance of irregular protrusions or shark scale-like patterns or loss of surface gloss on the surface of a polymer during extrusion of the polymer. As the shear rate at which melt fracture or sharkskin occurs increases, the processability of the corresponding polymer can be said to be excellent.

[0151] When measured by gel permeation chromatography (GPC), an olefin-based polymer according to an exemplary embodiment of the present invention may have a bimodal or multimodal molecular weight distribution.

[0152] Specifically, in the GPC graph of an olefin-based polymer according to an exemplary embodiment of the present invention, when the point where the tangent slope changes from a positive value to a negative value is a "peak", and the point where the tangent slope changes from a negative value to a positive value is a "valley", an olefin-based polymer according to an exemplary embodiment of the present invention may exhibit a bimodal or multimodal molecular weight distribution having two or more peaks.

[0153] In a specific example of the present invention, when an olefin-based polymer is represented in a Van Gurp-Palmen graph, an inflection point may exist.

[0154] Whether long branches are present in an ethylene-based polymer can be determined by, among other things, whether an inflection point exists in the Van Gurp-Palmen graph measured using a rheometer, whether it has a divergent trend as the complex modulus (G*) decreases, etc. In the Van Gurp-Palmen graph, as the complex modulus value on the x-axis decreases, the phase angle on the y-axis diverges, and as the complex modulus value increases, an inflection point exists. The characteristics of this graph indicate that the ethylene-based polymer contains many long branches.

[0155] As described later, in an olefin-based polymer film prepared from an olefin-based polymer according to an exemplary embodiment of the present invention, the generation of gels is suppressed. Therefore, it is determined that the existence of an inflection point on the Van Gurp-Palmen graph of an olefin-based polymer according to an exemplary embodiment of the present invention is due to the presence of long branches, and thus, it should be understood that an olefin-based polymer according to an exemplary embodiment of the present invention exhibits excellent high-speed processability.

[0156] In a specific example of the present invention, when the above olefin-based polymer is formed into a film having a thickness of 30 μm to 60 μm by blown film molding, the gel index (defined by the number of gels having a size of 0.05 mm or larger present in a random film area of 5 cm × 5 cm) may be 1 or less.

[0157] Olefin-based polymer film

[0158] According to an exemplary embodiment of the present invention, an olefin-based polymer film produced by molding the above-described olefin-based polymer is provided. When the olefin-based polymer according to an exemplary embodiment of the present invention is molded into a film having a thickness of 30 μm to 60 μm by blown film molding, the gel index of the film (defined by the number of gels having a size of 0.05 mm or more present in a random film area of 5 cm × 5 cm) is 1 or less.

[0159] The method for preparing an olefin-based polymer film according to an exemplary embodiment is not particularly limited, and a method known in the art to which the present invention pertains can be used. For example, the above-described olefin-based polymer can be processed by common methods such as blown film molding, extrusion molding, or casting molding to prepare an olefin-based polymer film. Among them, blown film molding is most preferred.

[0160] Examples

[0161] Hereinafter, the present invention will be described in more detail by way of examples and comparative examples. However, the following examples merely illustrate the present invention and do not limit the scope of the present invention.

[0162] Preparation Example 1

[0163] 26 mg of the transition metal compound of Chemical Formula 2-1, 58 mg of the transition metal compound of Chemical Formula 2-2, and 22 mg of the transition metal compound of Chemical Formula 5-1 were mixed with 16 g of a toluene solution of 10 wt% methylaluminoxane (MAO) in a glove box (Al / Zr = 150), and stirred at room temperature for 1 hour. Meanwhile, 4 g of silica (XP2402) was added to the reactor, and 30 ml of purified toluene was added and mixed. The solution of the transition metal compound was injected into the obtained silica slurry, and stirred in an oil bath at 75 °C for 3 hours. After completion of the loading and sufficient and complete separation of the solid / liquid, the supernatant was removed. The supported catalyst was washed 3 times with toluene and dried in vacuo at 60 °C for 10 hours to obtain 3.8 g of a composite supported catalyst in the form of a free-flowing powder.

[0164] Preparation Example 2

[0165] 3.8 g of a composite supported catalyst in the form of a free-flowing powder was obtained in the same manner as in Preparation Example 1, except that 38 mg of the transition metal compound of Chemical Formula 2-1, 46 mg of the transition metal compound of Chemical Formula 2-2, and 22 mg of the transition metal compound of Chemical Formula 5-1 were used.

[0166] Preparation Example 3

[0167] 3.8 g of the composite supported catalyst in the form of a free-flowing powder was obtained in the same manner as in Preparation Example 1, except that 12 mg of the transition metal compound of Chemical Formula 2-1, 58 mg of the transition metal compound of Chemical Formula 2-2, and 28 mg of the transition metal compound of Chemical Formula 1-4 were used.

[0168] Preparation Example 4

[0169] 3.8 g of the composite supported catalyst in the form of a free-flowing powder was obtained in the same manner as in Preparation Example 1, except that 13 mg of the transition metal compound of Chemical Formula 2-1, 80 mg of the transition metal compound of Chemical Formula 2-2, and 18 mg of the transition metal compound of Chemical Formula 1-1 were used.

[0170] Preparation Example 5

[0171] 3.8 g of the composite supported catalyst in the form of a free-flowing powder was obtained in the same manner as in Preparation Example 1, except that 26 mg of the transition metal compound of Chemical Formula 2-1, 114 mg of the transition metal compound of Chemical Formula 3-1, and 58 mg of the transition metal mixture of Chemical Formula 1-4 were used.

[0172] Preparation Example 6

[0173] 3.8 g of the composite supported catalyst in the form of a free-flowing powder was obtained in the same manner as in Preparation Example 1, except that 12 mg of the transition metal compound of Chemical Formula 2-1, 54 mg of the transition metal compound of Chemical Formula 3-1, and 28 mg of the transition metal compound of Chemical Formula 1-1 were used.

[0174] Preparation Example 7

[0175] 3.8 g of the composite supported catalyst in the form of a free-flowing powder was obtained in the same manner as in Preparation Example 1, except that 22 mg of the transition metal compound of Chemical Formula 2-1, 44 mg of the transition metal compound of Chemical Formula 2-3, and 28 mg of the transition metal compound of Chemical Formula 1-1 were used.

[0176] Preparation Example 8

[0177] 0.8 g of the transition metal compound of Chemical Formula 2-1, 3.8 g of the transition metal compound of Chemical Formula 2-2, and 1.9 g of the transition metal compound of Chemical Formula 5-1 were mixed with 1.1 kg of a toluene solution of 10 wt% methylaluminoxane (MAO) in a glove box (Al / Zr = 150), and stirred at room temperature for 1 hour. Meanwhile, 250 g of silica (XP2402) was added to the reactor, and 30 ml of purified toluene was added and mixed. The solution of the transition metal compound was injected into the obtained silica slurry, and stirred in an oil bath at 75 °C for 3 hours. After completion of loading and sufficient and complete separation of the solid / liquid, the supernatant was removed. The supported catalyst was washed 3 times with toluene and dried in vacuo at 60 °C for 10 hours to obtain 230 g of a composite supported catalyst in the form of a free-flowing powder.

[0178] Preparation Example 9

[0179] 230 g of a composite supported catalyst in the form of a free-flowing powder was obtained in the same manner as in Preparation Example 8, except that 0.8 g of the transition metal compound of Chemical Formula 2-1, 5 g of the transition metal compound of Chemical Formula 2-2, and 1.2 g of the transition metal compound of Chemical Formula 1-1 were used.

[0180] Preparation Example 10

[0181] 225 g of a composite supported catalyst in the form of a free-flowing powder was obtained in the same manner as in Preparation Example 8, except that 0.8 g of the transition metal compound of Chemical Formula 2-1, 3.8 g of the transition metal compound of Chemical Formula 2-2, and 1.8 g of the transition metal compound of Chemical Formula 1-4 were used.

[0182] Examples 1 to 2 and Comparative Examples 1 to 5

[0183] In a fluidized bed gas phase reactor, ethylene and 1-hexene were copolymerized using 10 mg to 100 mg of each of the supported catalysts obtained in Preparation Examples 1 to 7 in the presence of 0.6 ml of 1 M triisobutylaluminum (TIBAL) as a scavenger. The temperature in the reactor was maintained at 80 °C, the pressure of ethylene was 14 kgf / cm 2 , the amount of 1-hexene was 100 ml, and the total amount of hydrogen added was 1,300 ml. The polymerization conditions are shown in Table 1 below.

[0184] [Table 1]

[0185]

[0186] Example 3 and Comparative Examples 6 and 7

[0187] In a pilot-scale continuous fluidized bed gas-phase reactor, ethylene and 1-hexene were copolymerized using each of the supported catalysts obtained in Preparation Examples 8 to 10. The polymerization conditions are shown in Table 2 below.

[0188] [Table 2]

[0189]

[0190] Test Example

[0191] The physical properties of the olefin-based polymers obtained in the Examples and Comparative Examples were measured as follows. The measurement results are shown in Tables 3 and 4 below. For comparison, 8380, a high-speed processable product available from Hanwha Solutions, was used as Comparative Example 1.

[0192] (1) Melt index and melt flow ratio (MFR)

[0193] According to ASTM D 1238, each melt index was measured at 190 °C with a load of 21.6 kg and a load of 2.16 kg, and the ratio (MI 21.6 / MI 2.16 ) was calculated.

[0194] (2) Density

[0195] The density was measured according to ASTM D 1505.

[0196] (3) Gel permeation chromatography

[0197] Gel permeation chromatography-FTIR (GPC-FTIR) with the model name GPC-6 available from Polymer Char was used. The measurement was carried out at a temperature of 160 °C and trichlorobenzene was used as the solvent.

[0198] (4) Processability

[0199] The processability was measured using a Gottfert RG25 capillary rheometer. The measurement conditions were a circular orifice, a length of 20 mm, an effective length of 20 mm, a diameter / width of 2, a height of 0 mm, an operating angle of 180°, and at 230 °C, a piston diameter of 15 mm and a capillary diameter of 2 mm. The measurement was carried out based on the shear rate at which sharkskin or melt fracture occurred, and the shear rate was calculated by Equation 1 above.

[0200] (5) Gel index

[0201] A film with a thickness of 55 μm was prepared at 190 °C using a blown film forming machine available from Colliun, and the number of gels with a size of 0.05 mm or larger present in a film area of 5 cm × 5 cm was counted.

[0202] -0: A total of 10 or less

[0203] -1: A total of more than 10 and 30 or less

[0204] -2: A total of more than 30 and 50 or less

[0205] -3: A total of more than 50 and 100 or less

[0206] -4: A total of more than 100 and 200 or less

[0207] -5: A total of more than 200 (difficult to form film)

[0208] (6) Van Gurp-Palmen diagram

[0209] The Van Gurp-Palmen diagram is obtained by dynamic frequency scanning using an advanced rheometric expansion system (ARES). At 190 °C, measurements are carried out using a 25 mm parallel plate in the shape of a disc. In the Van Gurp-Palmen diagram, the x-axis represents the complex modulus (G, dyne / cm 2 ), and the y-axis represents the phase angle (d(δ)).

[0210] [Table 3]

[0211]

[0212] [Table 4]

[0213] Classification Example 3 Comparative Example 6 Comparative Example 7 Control Example 1 <![CDATA[I 2.16 (g / 10 minutes)]]> 0.7 0.62 0.84 0.74 <![CDATA[I 21.6 (g / 10 minutes)]]> 47.75 56.64 44.80 48.50 MFR 68 91 53 65 Mn 2,700 2,400 4,900 20,138 Mw 139,100 147,500 133,000 161,181 MWD (Mw / Mn) 50.9 61 26.9 8.0 Density (g / cc) 0.946 0.949 0.947 0.945 Gel Index 1 ＞5 2 1 Processability (1 / sec) 2,250 ND 3,000 1,000

[0214] As determined from Tables 1 and 2 above, the films prepared from the olefin-based polymers of Examples 1 and 2 within the scope of the present invention have inhibited gel formation. However, the number of gels in the films prepared from the olefin-based polymers of Comparative Examples 1 to 5 increases.

[0215] At the same time, as determined from Tables 3 and 4 above, the olefin-based polymer of Example 3 within the scope of the present invention has inhibited gel formation and shows a very high shear rate for high-speed processability. The olefin-based polymer of Example 3 has a gel degree similar to that of a commercial product (Control Example 1) and better high-speed processability. However, the number of gels in Comparative Example 6 increases significantly, and its shear rate cannot be measured. Comparative Example 7 has an excellent shear rate, but the number of gels increases compared to Example 3.

[0216] In addition, as determined from Figure 1Determined, different from Comparative Examples 6 and 7 and Control Example 1, the olefin-based polymer of Example 3 shows an inflection point in the Van Gurp-Palmen plot. This indicates that the olefin-based polymer of Example 3 has long branches, but the gel formation caused by the entanglement of the long branches is suppressed.

Claims

1. A method for preparing an olefin-based polymer, the method comprising: Ethylene and at least one α-olefin are polymerized in the presence of a metallocene catalyst composition comprising: (a) at least one first transition metal compound selected from transition metal compounds represented by Chemical Formulas 1 to 4 below; (b) at least one second transition metal compound selected from transition metal compounds represented by Chemical Formula 5 below; and (c) a cocatalyst compound, wherein the olefin-based polymer has a density of 0.930 g / cm 3 to 0.970 g / cm 3 , a melt index (I 2.16 ) measured at 190 °C under a load of 2.16 kg of from 0.1 g / 10 min to 2.0 g / 10 min, a weight average molecular weight of from 100,000 g / mol to 150,000 g / mol, and a shear rate of 1,500 seconds -1 or greater as defined by Equation 1 below, at which melt fracture or sharkskin phenomena occur: [Equation 1] [Chemical Formula 5] In the above equation, is the apparent shear rate (seconds -1 ), V is the volumetric flow rate generated by the piston (mm 3 / second), and R is the radius of the round hole capillary (mm). In the above chemical formula, l1 and m1 are each independently an integer from 0 to 5, l2, l3, l4 and m2 are each independently an integer from 0 to 4, m3 and m4 are each independently an integer from 0 to 2, p is the oxidation state of M and is +3, +4 or +5, q is the formal charge of the YZL ligand and is 0, -1, -2 or -3, M is each independently titanium (Ti), zirconium (Zr) or hafnium (Hf), X is independently selected from halogen, C 1-20 alkyl, C 2-20 alkenyl, C 2-20 alkynyl, C 6-20 aryl, C 1-20 alkyl C 6-20 aryl, C 6-20 aryl C 1-20 alkyl, C 1-20 alkylamido or C 6-20 arylamido, Q is each independently carbon (C), silicon (Si), germanium (Ge) or tin (Sn), Q' is an anionic leaving group and is independently of one another hydrogen, a substituted or unsubstituted C 1-40 hydrocarbyl, a substituted or unsubstituted C 1-40 heterohydrocarbyl, a heteroatom or a halogen, "Q" is a substituted or unsubstituted C 2-4 alkylene group, L is nitrogen, Y is nitrogen or phosphorus, Z is nitrogen or phosphorus, R1 to R4, R7, R8, R 18 and R 19 are each independently a substituted or unsubstituted C 1-20 alkyl, a substituted or unsubstituted C 2-20 alkenyl, a substituted or unsubstituted C 6-20 aryl, a substituted or unsubstituted C 1-20 alkyl C 6-20 aryl, a substituted or unsubstituted C 6-20 aryl C 1-20 alkyl, a substituted or unsubstituted C 1-20 heteroalkyl, a substituted or unsubstituted C 3-20 heteroaryl, a substituted or unsubstituted C 1-20 alkylamido, a substituted or unsubstituted C 6-20 arylamido, or a substituted or unsubstituted C 1-20 silyl, provided that these groups may or may not be independently connected to adjacent groups to form a substituted or unsubstituted, saturated or unsaturated C 4-20 ring, R5, R6, R9 and R 10 are each independently a substituted or unsubstituted C 1-20 alkyl, a substituted or unsubstituted C 2-20 alkenyl, a substituted or unsubstituted C 6-20 aryl, a substituted or unsubstituted C 1-20 alkyl C 6-20 aryl, a substituted or unsubstituted C 6-20 aryl C 1-20 alkyl, a substituted or unsubstituted C 1-20 heteroalkyl, a substituted or unsubstituted C 3-20 heteroaryl, a substituted or unsubstituted C 1-20 alkylamido, a substituted or unsubstituted C 6-20 arylamido, or a substituted or unsubstituted C 1-20 silyl, provided that R5 and R6 and R9 and R 10 may or may not be independently connected to each other to form a substituted or unsubstituted, saturated or unsaturated C 2-20 ring, R 11 and R 12 each independently is C 1-20 a hydrocarbyl group or a heteroatom-containing group, where the heteroatom is silicon, germanium, tin, lead or phosphorus, or R 11 and R 12 are capable of being connected to each other R 13 is absent or is hydrogen, C 1-20 alkyl, halogen or a heteroatom-containing group, R 14 and R 15 are each independently an alkyl group, an aryl group, a substituted aryl group, a cycloalkyl group, a substituted cycloalkyl group or a polycyclic system, and R 16 and R 17 each independently does not exist or can be hydrogen, alkyl, halogen, heteroatom, hydrocarbon group or heteroatom-containing group.

2. The method for preparing an olefin-based polymer according to claim 1, wherein the molar ratio between the first transition metal compound and the second transition metal compound is in the range of 10:1 to 1:

10.

3. The method for preparing an olefin-based polymer according to claim 1, wherein the transition metal compound of Chemical Formula 1 is at least one of the transition metal compounds represented by the following Chemical Formulas 1-1 to 1-4, the transition metal compound of Chemical Formula 2 is at least one of the transition metal compounds represented by the following Chemical Formulas 2-1 to 2-3, the transition metal compound of Chemical Formula 3 is the transition metal compound represented by the following Chemical Formula 3-1, and the transition metal compound of Chemical Formula 4 is the transition metal compound represented by the following Chemical Formula 4-1: [Chemical Formula 1-1][Chemical Formula 1-2][Chemical Formula 1-3] wherein n-Bu is n-butyl, t-Bu is tert-butyl, and Ph is phenyl.

4. The method for preparing an olefin-based polymer according to claim 1, wherein the transition metal compound of Chemical Formula 5 is the transition metal compound represented by the following Chemical Formula 5-1: [Chemical Formula 5-1] 5. The method for preparing an olefin-based polymer according to claim 1, wherein the cocatalyst compound comprises at least one selected from the compounds represented by the following Chemical Formula 6, the compounds represented by the following Chemical Formula 7, and the compounds represented by the following Chemical Formula 8: [Chemical Formula 6] [Chemical Formula 7] [Chemical Formula 8] [L-H] + [Z(A)4] - or [L] + [Z(A)4] - In the above chemical formula 6, n is an integer of 2 or greater, and R a is a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a halogen-substituted hydrocarbon group having 1 to 20 carbon atoms. In the above chemical formula 7, D is aluminum (Al) or boron (B), and R b , R c and R d are each independently a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogen-substituted hydrocarbon group having 1 to 20 carbon atoms, or an alkoxy group having 1 to 20 carbon atoms, and In the above chemical formula 8, L is a neutral or cationic Lewis base, [L-H] + and [L] + are Bronsted acids, Z is a Group 13 element, and A is independently of one another a substituted or unsubstituted aryl group having 6 to 20 carbon atoms or a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms.

6. The method for preparing an olefin-based polymer according to claim 5, wherein the compound represented by Chemical Formula 6 is at least one selected from the following: methylaluminoxane, ethylaluminoxane, isobutylaluminoxane, and butylaluminoxane.

7. The method for preparing an olefin-based polymer according to claim 5, wherein the compound represented by Chemical Formula 7 is at least one selected from the following: trimethylaluminum, triethylaluminum, triisobutylaluminum, tripropylaluminum, tributylaluminum, dimethylaluminum chloride, triisopropylaluminum, di-sec-butylaluminum, tricyclopentylaluminum, tripentylaluminum, triisopentylaluminum, trihexylaluminum, trioctylaluminum, ethyldimethylaluminum, methyldiethylaluminum, triphenylaluminum, tri-p-tolylaluminum, dimethylmethoxyaluminum, dimethylethoxyaluminum, trimethylboron, triethylboron, triisobutylboron, tripropylboron, and tributylboron.

8. The method for preparing an olefin-based polymer according to claim 5, wherein the compound represented by Chemical Formula 8 is at least one selected from the following: triethylammonium tetraphenylborate, tributylammonium tetraphenylborate, trimethylammonium tetraphenylborate, tripropylammonium tetraphenylborate, trimethylammonium tetrakis(p-tolyl)borate, trimethylammonium tetrakis(o,p-dimethylphenyl)borate, tributylammonium tetrakis(p-trifluoromethylphenyl)borate, trimethylammonium tetrakis(p-trifluoromethylphenyl)borate, tributylammonium pentaphenylborate, N,N-diethylaniline tetraphenylborate, N,N-diethylaniline pentaphenylborate, diethylammonium pentaphenylborate, triphenyl tetraphenylborate trimethyl tetraphenylborate triethylammonium tetraphenylaluminate, tributylammonium tetraphenylaluminate, trimethylammonium tetraphenylaluminate, tripropylammonium tetraphenylaluminate, trimethylammonium tetrakis(p-tolyl)aluminate, tripropylammonium tetrakis(p-tolyl)aluminate, triethylammonium tetrakis(o,p-dimethylphenyl)aluminate, tributylammonium tetrakis(p-trifluoromethylphenyl)aluminate, trimethylammonium tetrakis(p-trifluoromethylphenyl)aluminate, tributylammonium pentaphenylaluminate, N,N-diethylaniline tetraphenylaluminate, N,N-diethylaniline pentaphenylaluminate, diethylammonium pentaphenylaluminate, triphenyl tetraphenylaluminate trimethyl tetraphenylaluminate tripropylammonium tetrakis(p-tolyl)borate, triethylammonium tetrakis(o,p-dimethylphenyl)borate, triphenylcarbene tetrakis(p-trifluoromethylphenyl)borate and triphenylcarbene pentaphenylborate.

9. The method for preparing an olefin-based polymer according to claim 1, wherein the supported metallocene catalyst further comprises a support for supporting the supported complex transition metal compound, the cocatalyst compound, or both of them.

10. The method for preparing an olefin-based polymer according to claim 9, wherein the support comprises at least one selected from silica, alumina, and magnesia.

11. The method for preparing an olefin-based polymer according to claim 9, wherein based on 1 g of the support, the total amount of the supported complex transition metal compound supported on the support is 0.001 mmol to 1 mmol, and based on 1 g of the support, the total amount of the cocatalyst compound supported on the support is 2 mmol to 15 mmol.

12. The method for preparing an olefin-based polymer according to claim 1, wherein the α-olefin is one or more selected from the following: propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, and 1-hexadecene.

13. The method for preparing an olefin-based polymer according to claim 12, wherein the α-olefin is 1-hexene.

14. The method for preparing an olefin-based polymer according to claim 1, wherein the polymerization of ethylene and at least one α-olefin is carried out by gas-phase polymerization.

15. The method for preparing an olefin-based polymer according to claim 14, wherein the polymerization of ethylene and at least one α-olefin is carried out in a gas-phase fluidized bed reactor.

16. An olefin-based polymer, which is prepared by the method for preparing an olefin-based polymer according to any one of claims 1 to 15, and has a density of 0.930 g / cm 3 to 0.970 g / cm 3 , a melt index (I 2.16 ) measured at 190 °C with a load of 2.16 kg of 0.1 g / 10 min to 2.0 g / 10 min, a weight average molecular weight of 100,000 g / mol to 150,000 g / mol, and a shear rate of 1,500 seconds -1 or greater as defined by the following Equation 1, at which melt fracture or sharkskin phenomenon occurs: [Equation 1] Among them V and R are defined as in claim 1.

17. The olefin-based polymer according to claim 16, wherein the olefin-based polymer has a melt index (I 21.6 ) measured at 190 °C under a load of 21.6 kg and a melt index (I 2.16 ) measured under a load of 2.16 kg, and the ratio between them (melt flow ratio; MFR) is from 30 to 200.

18. The olefin-based polymer according to claim 16, wherein when the olefin-based polymer is represented by a Van Gurp-Palmen plot, there is an inflection point.

19. The olefin-based polymer according to claim 16, wherein when the olefin-based polymer is formed into a film having a thickness of 30 μm to 60 μm by blown film molding, the gel index of the film is 1 or less, and the gel index is defined by the number of gels having a size of 0.05 mm or more present in a 5 cm × 5 cm random film area.

20. An olefin-based polymer film prepared by forming the olefin-based polymer according to claim 16, wherein when the olefin-based polymer is formed into a film having a thickness of 30 μm to 60 μm by blown film molding, the gel index of the film is 1 or less, and the gel index is defined by the number of gels having a size of 0.05 mm or more present in a 5 cm × 5 cm random film area.

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